heiskell



Aug. 11, 1959 COMP TRACER COMPOSITION IGNITER COMPOSITION R. H. HEISKELL osmon FOR TRACER UNIT Filed June 29, 1948 WATERPROOF PAINT INVENTOR R. H. HEISKELL 400.073 Mk0 W ATTORNEYS United States Patent COMPOSITION FOR TRACER UNIT Raymond H. Heiskell, Compton, Calif.

Application June 29, 1948, Serial No. 35,960

' 2 Claims. or. 52-24 (Granted under Title 35, US. Code (1952), see. 266) This invention relates to a tracer ammunition unit especially adapted for use in 20 mm. projectile and more particularly, it concerns the combination of an improved sensitive tracer composition, and a slow burning non-flash igniter composition therefor.

Heretofore tracer ammunition used by our armed forces proved unsatisfactory especially when used in night encounters, in that, under conditions of darkness the flash therefrom upon ignition of the tracer composition by the igniter composition caused excessive flash and too much light streak at the muzzle of the gun, thus illuminating and disclosing the position of the gun to the enemy and confusing and misleading the gunner or fire director when aiming of the gun is accomplished by observation of the tracer streak. Such tracer ammunition also proved not altogether satisfactory when used inday encounters inasmuch as when the tracer composition was ignited the tracer streak emitted therefrom was of insuflicient intensity to permit the fire director to follow the tracer streak as the projectile traveled along a trajectory.

The present invention is especially adapted to obviate the above mentioned flash and bright streak of light occurring at the gun muzzle as the projectile is fired therefrom, and also producing a tracer streak of sufficient intensity to permit the gunner or fire director to observe the tracer streak and follow the flight of the projectile either at night or during the day.

Accordingly, it is an object of the invention to provide a composition for a tracer unit for a projectile comprising a new and improved light emitting trace composition including a slow burning non-flash igniter composition therefor.

Another object is to provide a new and improved igniter composition for a tracer unit for a projectile adapted to delay ignition of a new and improved tracer composition for a predetermined period of time after the projectile has been fired from a gun and traveled a substantial distance from the muzzle thereof and in which the tracer composition, when ignited by the igniter composition, produces a tracer streak of sufficiently bright intensity to permit the gunner to follow the flight of the projectile either at night or during the day as the projectile travels along a trajectory.

Other objects and advantages of the present invention will become more apparent during the course of the following description taken in connection with the accompaying drawing.

In accordance with the present invention the new and improved slow burning non-flash or dark igniter composition for the tracer unit is composed of a mixture of barium peroxide, antimony sulfide, magnesium, and a lubricant of graphite, and a sensitive light emitting tracer composition composed of a mixture of magnesium, strontium nitrate, strontium tartrate, hexachlorobenzene, charcoal, and a binder of stearic acid.

Referring to the drawing, each of the aforesaid mixtures is mixed separately and pressed or moulded into pellet form thereby to form a slow burning non-flash igniter composition pellet and a sensitive light emitting tracer composition pellet, the tracer unit being completed by pressing the igniter pellet onto the tracer pellet and thereafter coating the entire tracer-igniter unit with a moistureproof paint such, for example, as waterproof paint of the type known to those skilled in the art as Bakelite Varnish No. XV-1657.

The igniter composition of the present invention may be obtained by moulding a mixture of the following ingredients, the ingredients being proportioned by percentage by weight such, for example, as 76-78.4% barium peroxide, l8.4-23% antimony sulfide, 02.2% magnesium, and .l-l% of graphite. In preparing the ingredients of the igniter composition it has been found that the best results are obtained when the barium peroxide, antimony sulfide, and magnesium are of such proportions as to pass through a US. standard sieve, mesh size 200 and the graphite is of such proportion as to pass through a US. standard sieve, mesh size 325.

Now, the nature and purpose of the igniter unit of the present invention having been indicated in a general way, the following specific example of the igniter composition thereof is illustrated together with the mesh size of the sieve used. In this example the ingredients of the igniter composition are given in percentages by weight.

Slow burning non-flash igniter composition The tracer composition of the present invention may be obtained by moulding a mixture of the following ingredients, the ingredients being proportioned by percentage by weight such, for example, as 3l.838% magnesium, 30.938% strontium nitrate, 12-27.3% stron tium tartrate, 4.6-5 hexachlorobenzene, 20.9% charcoal, and 4.55% stearic acid. In preparing the ingredients of the tracer composition, it has been found that the best results are obtained when all the ingredients comprising the tracer composition are of such proportions as to pass through a US. standard sieve, mesh size 100.

Now, the nature and purpose of the tracer unit of the present invention having been indicated in a general way, the following specific example of the tracer composition thereof is illustrated together with the mesh size of the sieve used.

for both daylight and night use, a small percentage of hexachlorobenzene was added to the tracer mixture to improve this color etfect of the trace streak and it was also found that by the addition of a small amount of pulverized charcoal to the tracer composition the ignition thereof was improved, as the addition of the char coal when mixed with the other fine powder ingredients of the tracer composition in the aforesaid proportions decreased the compressibility of the entire mixture, thus making it more porous and improving the ignition thereof.

In preparing the igniter composition it was found that when the barium peroxide, antimony sulfide, and magnesium were mixed with the graphite in the aforesaid proportions, the ignition sensitivity characteristics thereof proved entirely satisfactory and the combustion thereof was sufiiciently retarded to ignite the tracer composition in predetermined time delayed relation with respect to ignition of the igniter composition. It was also found that by maintaining the particle size of the antimony sulfide smaller than 200 mesh size, the frictional sensitivity of the particles of which the igniter composition is composed is sufficiently low to prevent premature detonation of the mixture. Furthermore, proper functioning of the tracer unit is obtained when the tracer unit is loaded into the tracer cavity arranged in the projectile with a serrated ram at a pressure such, for example, as from 30,00046,000 p.s.i.

From the foregoing description it will be understood that a composition for a tracer unit for a projectile has been compounded and constructed in which the igniter composition thereof is adapted to delay ignition of the light emitting tracer composition thereof for a predetermined period of time after ignition of the igniter composition as the projectile is fired from a gun whereby ignition of the tracer composition will occur a substantial distance from the muzzle of the gun such, for exam ple, as from 75 to 125 yards, thereby preventing area illumination of the battery, and also preventing the flash upon ignition of the trace composition from producing a blinding effect on the gunner.

Furthermore, the present invention is adapted to improve the daylight visibility of the tracer streak emitted from the tracer composition, such tracer streak being sufiiciently bright to permit the gunner to observe and follow the streak as the projectile travels along a trajectory. From the foregoing description it will be understood that ignition of the tracer composition by the igniter composition and the appearance of the tracer streak therefrom will not occur until a predetermined period of time has elapsed after ignition of the igniter composition.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A composition for a tracer unit comprising a tracer mixture containing about 31.8% magnesium, about 30.9% strontium nitrate, about 27.3% strontium tartrate, about 4.6% hexachlorobenzene, about 0.9% charcoal, and a binder therefor composed of about 4.5% stearic acid.

2. A light emitting pyrotechnic composition consisting essentially of 31.8% to 38% magnesium, from 30.9 to 38% strontium nitrate, from 12 to 27.3% of strontium tartrate, from 4.6 to 5% hexachlorobenzene, from 2 to .9% charcoal, and about 5% stearic acid.

References Cited in the file of this patent UNITED STATES PATENTS 1,708,174 Hendler Apr. 9, 1929 2,115,047 Stevenson Apr. 26, 1938 2,362,502 Schladt Nov. 14, 1944 2,410,801 Audrieth Nov. 12, 1946 FOREIGN PATENTS 7,562 Great Britain of 1898 349,839 Great Britain June 4, 1931 

1. A COMPOSITION FOR A TRACER UNIT COMPRISING A TRACER MIXTURE CONTAINING ABOUT 31.8% MAGNESIUM, ABOUT 30.9% STRONTIUM NITRATE, ABOUT 27.3% STRONTIUM TARTRATE, ABOUT 4.6% HEXACHLOROBENZENE, ABOUT 0.9% CHARCOAL, AND A BINDER THEREFOR COMPOSED OF ABOUT 4.5% STEARIC ACID. 